1. Technical Field
The present invention relates, in general, to vibration motors and, more particularly, to a vibration motor which has a detent magnet to stop a coil in the middle between the poles of a magnet, thus allowing the coil to be always placed at a location at which maximum starting torque is generated, therefore maximally securing starting torque and perfectly eliminating a dead point.
2. Description of the Related Art
Recently, as the use of personal information and communication devices such as mobile terminals or mobile phones has been increasing, most of the devices have used a vibration motor which transmits a receiving signal to a user in a silent manner so that other people are not inconvenienced. Vibration motors used in most electronic devices have been competitively produced by many manufacturing companies so as to realize superior performance and good quality in comparison with their cost.
Currently, a two-phase vibration motor is being produced to achieve good performance and reliable quality. Meanwhile, a single-phase vibration motor inevitably has the defect of having a dead point at which starting is impossible. However, the single-phase motor provides many advantages to motor producers and users, because the single-phase motor reduces the number of parts and the number of processes, thus reducing cost and enhancing quality. Therefore, research has been made into a flat single-phase motor which eliminates the dead point and uses a magnet with detent force.
FIG. 9 illustrates the arrangement of devices for generating the detent force of a conventional vibration motor so as to precisely limit the stop position of a rotor, this being the conventional method of eliminating the dead point. As shown in FIG. 9, the method of designating a starting position at a point slightly deviating from a maximum torque area cannot stop a coil between the N and S poles at which maximum starting torque may be generated.
Accordingly, there is an urgent need for the development of a flat single-phase motor which can eliminate the dead point and generate maximum torque without deteriorating performance.